The Earth surface is exposed to chemical weathering, physical erosion and biological activity, which shape landscapes and set biogeochemical cycles. The breakdown of rock into soil is controlled by the complex interplay of geochemical, geomorphological, hydrological and biological processes together with the effect of human activities. Furthermore, the geochemical and biochemical cycles associated with chemical weathering have direct impacts and feedbacks that extend well beyond soils. Identification and quantification of the processes that govern the evolution of the Critical Zone – Earth’s living skin – requires multiple tools from across an array of disciplines. The application of multiple isotope systems including traditional isotopes (e.g., of C, H, O, S, Sr), cosmogenic nuclides (e.g. 10Be, 26Al), short-lived natural U and Th-series radionuclides and non-traditional stable isotopes (e.g., Li, Mg, Si, Ca, Fe, Cr, Zn, Cu), together with other geochemical and mineralogical tracers (e.g., element ratios, alteration indices), enable us to decipher linkages and mechanisms of weathering processes and quantify dissolved and particulate fluxes across varying lithologies, tectonic settings, climatic conditions and anthropogenic influences. Critical zone science is a multidisciplinary research field - this session invites contributions encompassing field studies, laboratory experiments, exploring the analytical frontiers of element and isotope measurements and modelling approaches to understand the processes driving present and past development and change of the Earth surface.